Let me tell you that I am a boy, but I think I can still help you a bit.
Firtsly, don't worry too much, every girl has to face it during her puberty, that's a rule of nature. I have heard that it can be painful, or it might not be even painful. Everyone's body is different and they work differently, so anyone can't guarantee. Periods are necessary for a girl to be able to reproduce in the future. At first, it might feel disgusting, weird or nasty. But after it becomes a habit, it'll not make you feel like that anymore. Therefore, my advice is ''keep calm and take it easy''.
Hope this helps! :)